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Wang S, Lin C, Zhao L, Gong X, Zhang M, Zhang H, Hu P. Identifying isomers in Chinese traditional medicine via density functional theory and ion fragmentation simulation software QCxMS. J Chromatogr A 2024; 1730:465122. [PMID: 38941796 DOI: 10.1016/j.chroma.2024.465122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2024] [Revised: 06/22/2024] [Accepted: 06/24/2024] [Indexed: 06/30/2024]
Abstract
In the realm of electrospray ionization mass spectrometry (ESI-MS), distinguishing among isomers poses a significant challenge due to the minimal spectral differences that often arise from their subtle structural differences. This makes the accurate identification of these compounds through solely experimental spectra a daunting task. Computational chemistry has emerged as a pivotal tool in bridging the gap between experimental observations and theoretical understanding. This study used the MS fragmentation simulation software, QCxMS, to model the spectra of five groups of isomers, encompassing 11 compounds, found in the traditional Chinese medicine, Zhishi Xiebai Guizhi Decoction. By comparing the spectra predicted through computational methods with those derived from Ultra-high performance liquid chromatography-quadrupole-time of flight-mass spectrometry (UPLC-Q-TOF-MS) experiments, it was observed that, following the optimization of simulation parameters, QCxMS was capable of generating reliable spectra for all examined compounds. Notably, the data calculated under both GFN1-xTB and GFN2-xTB levels exhibited no significant discrepancies. Further analysis enabled the identification of the principal fragments of the 11 compounds from the theoretical data, facilitating the deduction of their fragmentation pathways. The Density Functional Theory (DFT) method was subsequently applied to compute the primary fragmentation energies of these compounds. The findings revealed a congruence between the energy data calculated using both thermodynamic and kinetic approaches and the observed fragment abundance of the isomers. This alignment providing a more precise theoretical framework for understanding the mechanisms underlying the generation of fragment ion differences among isomers.
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Affiliation(s)
- Shuai Wang
- Shanghai Key Laboratory of Functional Materials Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Chuhui Lin
- Shanghai Key Laboratory of Functional Materials Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Linghao Zhao
- Shanghai Key Laboratory of Functional Materials Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Xueqing Gong
- School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Min Zhang
- Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China
| | - Hongyang Zhang
- Shanghai Key Laboratory of Functional Materials Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Ping Hu
- Shanghai Key Laboratory of Functional Materials Chemistry, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China.
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Kirschbaum C, Greis K, Torres-Boy A, Riedel J, Gewinner S, Schöllkopf W, Meijer G, Helden GV, Pagel K. Studying the Intrinsic Reactivity of Chromanes by Gas-Phase Infrared Spectroscopy. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2024; 35:1950-1958. [PMID: 38950388 PMCID: PMC11311547 DOI: 10.1021/jasms.4c00216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2024] [Revised: 06/11/2024] [Accepted: 06/19/2024] [Indexed: 07/03/2024]
Abstract
Tandem mass spectrometry is routinely used for the structural analysis of organic molecules, but many fragmentation reactions are not well understood. Because several potential structures can correspond to a measured mass, the assignment of product ions is ambiguous using mass spectrometry alone. Here, we combine mass spectrometry with high-resolution gas-phase infrared spectroscopy and computational chemistry tools to identify product ion structures and derive collision-induced fragmentation mechanisms of the chromane derivatives Trolox and Methyltrolox. We find that protonated Trolox and Methyltrolox fragment identically via dehydration and decarbonylation, while deprotonated ions display substantially diverging reactivities. For deprotonated Methyltrolox, we observe unusual radical fragmentation reactions and suggest a [1,2]-Wittig rearrangement involving aryl migration in the gas phase. Overall, the combined experimental and theoretical approach presented here revealed complex proton dynamics and intramolecular rearrangement reactions, which expand our understanding on structure-reactivity relationships of isolated molecules in different protonation states.
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Affiliation(s)
- Carla Kirschbaum
- Freie
Universität Berlin, Institute of Chemistry
and Biochemistry, 14195 Berlin, Germany
- Fritz
Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | - Kim Greis
- Freie
Universität Berlin, Institute of Chemistry
and Biochemistry, 14195 Berlin, Germany
- Fritz
Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | | | - Jerome Riedel
- Freie
Universität Berlin, Institute of Chemistry
and Biochemistry, 14195 Berlin, Germany
- Fritz
Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | - Sandy Gewinner
- Fritz
Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | | | - Gerard Meijer
- Fritz
Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | - Gert von Helden
- Fritz
Haber Institute of the Max Planck Society, 14195 Berlin, Germany
| | - Kevin Pagel
- Freie
Universität Berlin, Institute of Chemistry
and Biochemistry, 14195 Berlin, Germany
- Fritz
Haber Institute of the Max Planck Society, 14195 Berlin, Germany
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Zhang B, Hao M, Xiong J, Li X, Koopman J. Ab initio molecular dynamics calculations on electron ionization induced fragmentations of C 4F 7N and C 5F 10O for understanding their decompositions under discharge conditions. Phys Chem Chem Phys 2023; 25:7540-7549. [PMID: 36857631 DOI: 10.1039/d2cp03498k] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
C4F7N and C5F10O are the most promising SF6 alternatives as eco-friendly insulating gaseous mediums in electrical engineering. It is necessary to clarify their electrical stability and decomposition mechanisms. In this work, we first introduced our experimental results for decomposition products of C4F7N/CO2 and C5F10O/synthetic air mixtures under partial discharge and spark discharge conditions. Then, we performed ab initio molecular dynamics (AIMD) simulations on the typical decomposition products. The simulations were performed under standard electron impact mass spectrometry (EI-MS); thus, the statistical results of the mass spectra were compared with those of the experimentally obtained standard mass spectra from the NIST database. The AIMD simulation method in simulating the electron-induced ionization process was verified and found to be reliable. Finally, the calculations were also performed for C4F7N and C5F10O with incident electron energies of 20 eV and 70 eV, respectively. The dominant pathway for both gases is the formation of CF3+ with the fracture of the C-C bond. The AIMD simulation is able to predict the decomposition channels after electron-impact ionization without any preconceived knowledge of fragmentation pathways, which provides a novel insight into understanding the decomposition mechanisms of C4F7N and C5F10O under different discharge conditions with different energies.
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Affiliation(s)
- Boya Zhang
- State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an, Shaanxi Province 710049, China.
| | - Mai Hao
- State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an, Shaanxi Province 710049, China.
| | - Jiayu Xiong
- State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an, Shaanxi Province 710049, China. .,State Grid Sichuan Electric Power Research Institute, Chengdu, Sichuan Province 610041, China
| | - Xingwen Li
- State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an, Shaanxi Province 710049, China.
| | - Jeroen Koopman
- Mulliken Center for Theoretical Chemistry, Institute of Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115 Bonn, Germany
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Fu D, Habtegabir SG, Wang H, Feng S, Han Y. Understanding of protomers/deprotomers by combining mass spectrometry and computation. Anal Bioanal Chem 2023:10.1007/s00216-023-04574-1. [PMID: 36737499 DOI: 10.1007/s00216-023-04574-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 01/19/2023] [Accepted: 01/27/2023] [Indexed: 02/05/2023]
Abstract
Multifunctional compounds may form different prototropic isomers under different conditions, which are known as protomers/deprotomers. In biological systems, these protomer/deprotomer isomers affect the interaction modes and conformational landscape between compounds and enzymes and thus present different biological activities. Study on protomers/deprotomers is essentially the study on the acidity/basicity of each intramolecular functional group and its effect on molecular structure. In recent years, the combination of mass spectrometry (MS) and computational chemistry has been proven to be a powerful and effective means to study prototropic isomers. MS-based technologies are developed to discriminate and characterize protomers/deprotomers to provide structural information and monitor transformations, showing great superiority than other experimental methods. Computational chemistry is used to predict the thermodynamic stability of protomers/deprotomers, provide the simulated MS/MS spectra, infrared spectra, and calculate collision cross-section values. By comparing the theoretical data with the corresponding experimental results, the researchers can not only determine the protomer/deprotomer structure, but also investigate the structure-activity relationship in a given system. This review covers various MS methods and theoretical calculations and their devotion to isomer discrimination, structure identification, conformational transformation, and phase transition investigation of protomers/deprotomers.
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Affiliation(s)
- Dali Fu
- State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering and Environment, China University of Petroleum-Beijing, Beijing, 102249, People's Republic of China
| | - Sara Girmay Habtegabir
- State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering and Environment, China University of Petroleum-Beijing, Beijing, 102249, People's Republic of China
| | - Haodong Wang
- State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering and Environment, China University of Petroleum-Beijing, Beijing, 102249, People's Republic of China
| | - Shijie Feng
- State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering and Environment, China University of Petroleum-Beijing, Beijing, 102249, People's Republic of China
| | - Yehua Han
- State Key Laboratory of Heavy Oil Processing, College of Chemical Engineering and Environment, China University of Petroleum-Beijing, Beijing, 102249, People's Republic of China.
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